KENNEDY SPACE CENTER, FLA. -- Workers in the Payload Hazardous Servicing Facility take a close look at the aeroshell and cruise stage of one of the Mars Exploration Rovers (MER). The upper portion is the heat shield on the aeroshell. The two rovers , aeroshell and lander will undergo a full mission simulation while at KSC. All flight elements will then be integrated. After spin balance testing, each spacecraft will be mated to a solid propellant upper stage booster that will propel it out of Earth orbit. The rovers will serve as robotic geologists to seek answers about the evolution of Mars, particularly for a history of water. The rovers will be identical to each other, but will land at different regions of Mars. Launch of the MER-1 is scheduled for May 30. MER-2 will follow June 25.